2004 A6 3.0 with 79000 miles, and it just started going from Drive to Sport mode while driving it with out me shifting it. Sort of a shudder, then engages itself from drive to sport. If you push it into sport from there back to drive, it doesn't engage. While it is in Sport, if you try to put it into triptronic, it doesn't engage...only 3 days since this started with limited driving. As of this morning, when I put it in reverse, it engaged, but would only go very slowly, and when I gave it gas, the engine would rev, but the car wouldn't go any faster....any ideas??

 

I think your in that "limited drive mode" I'm not sure the official name of it is. You have a shifting issue in the tranny and its putting it in a turtle mode.

 

Your in Limp mode time to bring it in to the stealer.